The functional density of electronic devices is an important measure of the power and utility of integrated circuits. Significant resources are continually expended in search of ways to downscale minimum device geometries and therefore increase the functional density of electronic devices. The development of nanoelectronics, which makes use of electron quantum effects, has presented an electronics regime that may provide for substantial decreases in device geometries over devices predominantly used in integrated circuits today.
Until very recently, nanoelectronic quantum effect devices have largely been the subject of study and laboratory experimentation. However, advancements in fabrication techniques have increased the viability of such devices in a wide range of applications.
Because of demonstrated switching capabilities of quantum effect devices, the successful application of such devices in digital electronics appears promising. Prior art devices have been able to switch current in quantum effect devices through use of electric fields. For example, Chou, Allee, Pease, and Harris have disclosed such a device in their paper "Lateral Resonant Tunneling Transistors Employing Field-Induced Quantum Wells and Barriers," Proceedings of the IEEE, Volume 79, No. 8, August 1991, pp. 1131-1139. As another example, Yang, Kao, and Shih discussed a Stark-Effect Transistor in their paper "New Field Effect Resonant Tunneling Transistor: Observations of Oscillatory Transconductance," Appl. Phys. Lett. 55 (26N), 25 Dec. 1989, pp. 2742-2744.
Although advances have been made in the development of quantum effect devices, progress has been slow for applications in digital electronics. For example, devices such as those disclosed by Chou, et al. display certain characteristics of semiconductor switching devices. Through the use of electric fields, quantum wells can be created between depletion-region-potential-barriers, and resonant tunneling can be observed. Thus, electric current can be switched on or off, depending upon the strength of the electric fields. The performance of such devices, however, is highly dependent upon precise dopant concentrations, and they must be operated only at low temperatures. Devices such as those disclosed by Yang, et al. make use of physical, horizontal potential barriers. In such devices, current flow is affected through use of electric fields generated between front and back gates.
None of the prior art devices have provided for the performance of multiple input digital logic functions in a single device. Therefore, a need has arisen for a quantum effect device that allows for a plurality of inputs, such that logical functions may be realized by switching current "ON" and "OFF" by application of predetermined potentials to each of the inputs.